Closed-loop gap bridging control for remote laser welding of aluminum components based on first principle energy and mass balance

Remote laser welding (RLW) has been successfully deployed for steel products, particularly doors, closures, and hang-on parts with overlap seam welding configurations. The growing demand for light-weight body structures has created interesting opportunities to apply RLW to fillet welding with the application to aluminum components. However, seamless migration from seam welding of steel to fillet welding of aluminum is limited by the following challenges: weld seam tracking capability to compensate trim edge variations; hot cracking resulting from the interaction between material chemistry and heat dissipation; and form error variations leading to unwanted part-to-part gaps, which in the absence of filling material must be bridged only by autogenous material. This paper focuses on the aspect of the part-to-part gap bridging and proposes a model to select and adjust welding process parameters to control the volume of the molten pool and achieve gap bridging. The proposed model is based on the observation that gap bridging is impaired by five distinct failure modes. Each mode is modeled by first-principle energy and mass balance criteria. Selection of welding parameters is presented by a set of gap bridging capability charts which helps to prevent failure modes and select feasible weld process parameters.